Potato residue was generated during the process of potato starch production.It contains a lot of starch and dietary fiber and small amounts of protein.It is a valuable resource.In this paper α-amylase and glucoamylase were used to treat potato residue.And then the liquid portion was separated and fermented into edible protein.The solid part was bleached,modified to dietary fiber.Thus the potato residue was fully used.This study designed the process,selected the enzymes and optimized the process conditions.The protein and dietary fiber's physical and chemical properties were determined.